1G Need some serious help with my 1g that died on me. Suspect bad ecu or slung rod/bearing.

[Zander]

Okay so I haven't had time to work on it in about 5 months but I finally have some vacation so I want to get my 1g up and running. So heres the story. I got a 1g tsi bone stock. It since has had the ac removed, the evap removed, and the fiav blocked off. All this was done following the vfaq's to the t. Used quality blockoff plates and sealed everything.

The car has had idle surge since i bought it. I suspected the throttle body shaft seals of being bad. I pulled the throttle body, cleaned it of carbon, replaced the seals, and reinstalled with new gaskets. I let the car sit for about an hour to allow the small dot of locktite to cure and then i test drove it. Everything was fine for about 10 minutes of the drive when the engine stuttered on me mid turn. Any time i let the engine fall under 3.5k rpm it sounded like a cylinder stopped firing. Above 3.5k rpm and it sounded fine like everything was running clockwork. But under it sounded like a lawn mower running on 2 cylinders and just bad. I limped the car home and shut it off. It wouldn't restart after i let it cool off. Found out the fuel pump wasn't kicking on.

So to troubleshoot the fuel pump, i jumpered the test point by the firewall and it kicked right on. I had some trouble testing my spark plug cables so i replaced those and the plugs while i was at it. Got good spark on all cylinders. I jumpered the fuel pump again and tried to crank, and after about 10 seconds of cranking it started and sounded like a lawnmower still. So I shut it down again. I'm dropping the oil pan this afternoon to look for metal shavings and anything out of place to rule out a slung rod or spun bearing. But I need help after that. I'm leaning towards an ecu issue at the moment as it was a used ecu i pulled from a wrecker. I'm assuming the mpi is good since i can jumper the test port and the pump kicks on. The only other thing that i can guess would cause an issue like this would be the cas. I don't have the technical finesse to feel comfortable removing and testing the CAS. The timing is good though, it didn't jump timing although it sounds like that is what happened. either way. Can anyone spitball some ideas to test? Anyone ever heard of anything like this before? It was building boost while I was driving it so it's not a limp mode as i'd assume that wouldn't allow me to build boost. And I don't think a boost leak would cause this scale of an issue. Still, all replies are useful, i really need a hand just wrapping my head around possible causes for the issue.

 

[Bo0sTeD 4G63]

Did you check to make sure you are getting the correct amount of fuel pressure? Also check the compression of the motor before you drop the oil pan to make sure the engine has good compression.

 

[Zander]

Compression seems good but I'm like 30 minutes away from dropping fuel pan. Without testing it, I am assuming I am getting good fuel pressure since the car will turn over after some cranking and will stay running until i cut it off. As far as I know there is no easy way to test fuel pressure, so i was just going off do i have fuel, yes
do i have spark, yes
still issues with starting, looking at ecu and cas

 

[second_amendment]

check the oil for some metal debris, if you see some nice size flakes most likely you bearing spun, some glitter is normal. it sounds like its a fuel or ignition issue.

 

[Travis Grant]

Don't count out a bad vacuum leak. It's better to cross out the basics before venturing down another path. But from the way you describe it sounds like something more mechanical than electronics as the problem goes away above 3.5k. Rule out the basics first! Good luck!

 

[dsmrafa]

did you check your conections of the cam sensor7cas? what about the power transistor unit? did you check if there is a problem with an inyector? the fouling cylinders are one aside of the other?(if they are maybe there is a fouling head gasket....) good luck!!!

 

[nwBryce89]

Did you check to see what cylinders were not firing. Get a compression tester if you don't already have one. You said car sat a while, I would check and make sure your injectors are not plugged. If your ecu is bad it is very easy to tell. Use a multimeter on the diagnostic port to pull code and when you turn key on cel should come on for five secs then shut off, also you boost Guage should zero out if it does not do these things then it's probably bad.